An innovative new approach is presented that addresses the challenges of design in a constantly changing environment. New solutions that satisfy changing requirements are generated by rapidly reconfiguring ongoing projects and effectively reusing trusted designs. Design is essentially a process of generating knowledge about how to build new systems. Reuse is difficult because this knowledge is amorphous and difficult to access. Hierarchical platform-based engineering is used to structure and categorize this knowledge to make it easily accessible. This approach has three essential components: 1) Hierarchical platform-based design method organizes design projects into a structured library; 2) Transformational systems engineering and concurrent risk assessment are used to capture complex interactions between different CPS elements. These captured interactions help assess reusability and reconfigurability of each element; 3) A new design flow integrates platform-based design methods into the overall design workflow. Detailed examples are presented to illustrate the use of the new approach.